Android Question SHA1 conflict GCP and Firebase

So I need Firebase Auth in my project, therefore I added my SHA1 in Firebase.
Now I need to add Google's Translation API Which needs OAUTH.

As seen in Erel's Tutorial, we need to generate a client ID for this.
GCP needs SHA1 key too:







The problem is, I cannot use the same SHA1 key for firebase and OAUTH
When I try to add the key to GCP second:


when I try to add the key to firebase:


So this makes it impossible(?) to use OAuth with firebase auth in the same project?
Ad far as I know, we can use multiple debug keys in Android Studio, so normally developers do not have any issues.

unfortunately in B4A, it is not possible to have multiple keys. What is the solution here?

 

So how can I solve this?
I took a look around and cannot find any solution

 

The solution here only explains to delete the SHA1 key from any other firebase projects that are using it.

No other projects are using the same key, except the same project in GCP.

If I omit the key i will not be able to use google auth.

 

I have a lot of (huge) apps using Google services. Never had issues (except one caused by me )